A sterile drape is used in some operating rooms to separate a sterile field for a surgical procedure. For example, some operating rooms include a guidance station that tracks movement of various objects in the operating room. Such objects include, for example, a surgical instrument and anatomy of the patient. The guidance station tracks these objects for purposes of displaying their relative positions and orientations to the surgeon and, in some cases, for purposes of controlling or constraining movement of the surgical instrument relative to a predefined path or anatomical boundary. Many components of the guidance station cannot be adequately and/or easily sterilized. As such, a sterile drape is used to separate at least some of the components of the guidance station from the sterile field.
The guidance station includes a localizer that includes a camera unit. The camera unit includes optical sensors, e.g., charge-coupled devices (CCD), for tracking the objects in the operating room. Specifically, the camera unit tracks the position of tracking devices fixed to objects in the operating room such as surgical instruments and anatomy of the patient. The optical sensors of the localizer receive light signals emitted from the tracking devices, e.g., with the use of light emitting diodes (LEDs) fixed to the tracking devices. Based on the positions of the tracking devices, the guidance station calculates the position and/or orientation of the surgical instrument and the anatomy of the patient.
An unobstructed view is sought between the optical sensors of the camera unit and the tracking devices so that the optical sensors can accurately detect the light signals transmitted by the tracking devices. The tracking devices are in the sterile field on the surgical instruments and on the anatomy of the patient. The camera unit cannot be adequately and/or easily sterilized, so the sterile drape separates the camera unit from the sterile field of the operating room and, thus, separates the camera unit from the tracking devices.
The sterile drape can interfere with proper light detection by the camera unit. For example, wrinkles in the sterile drape between the optical sensors and the tracking devices interfere with the ability of the optical sensors to adequately detect the tracking devices. As another example, if the drape extends at a transverse plane relative to the optical sensors, i.e., is not co-planar with the optical sensors, the drape can distort the light detection of the camera unit. As such, there remains an opportunity to provide an adequate view between the optical sensors of the camera unit outside of the sterile field and the tracking devices inside the sterile field so that the optical sensors can accurately detect the tracking devices.